1. Field of the Invention
The present invention relates to a multiprojection system that provides display using images projected by a plurality of projectors as well as a method of acquiring correction data in the multiprojection system.
2. Description of the Related Art
In a multiprojection system a plurality of projectors project images on a screen to obtain one image. Accordingly, measures must be taken to, for example, make the joints between the projected images unnoticeable. Thus, a calibration image is projected on the screen, and the projected image is captured using capturing means such as a digital camera. Then, various corrections are executed on the basis of image data obtained by the capturing (for example, refer to Jpn. Pat. Appln. KOKAI Publication No. 2002-72359 and Jpn. Pat. Appln. KOKAI Publication No. 2002-116500).
Even for a black level image in which R, G, and B signal levels are all zero, the projector outputs light having a specified luminance. Accordingly, the black level must be corrected (offset correction). However, in the prior art, the calibration image is captured without separating R, G, and B colors from one another. Thus, if a dark image is displayed, the colors may be nonuniform within each projector or between the projectors. This degrades display quality.
It is an object of the present invention to provide a multiprojection system that can improve display quality by reducing the color nonuniformity within each projector or between projectors, as well as a method of acquiring correction data in the multiprojection system.
According to a first aspect of the present invention, there is provided a multiprojection system that displays one color image by joining a plurality of color images projected by respective projectors. The system includes an image capturing section including an optical section having a plurality of filter characteristics corresponding to a plurality of basic colors constituting the color image projected by the projectors, and capturing an image of each of the basic colors via the optical section; and a calculating section calculating offset correction data for each of the basic colors on the basis of a luminance distribution of offset light of each of the basic colors obtained by allowing the image capturing section to capture a black level image projected by the projectors.
The present invention may include following embodiments.
The multiprojection system further includes a correcting section correcting an image signal input to the projector using the offset correction data calculated by the calculating section.
Wavelength ranges of the filter characteristics do not overlap one another.
The optical section has a plurality of filters corresponding to the plurality of filter characteristics, and the plurality of filters can be switched by a mechanical operation.
The optical section has a tunable filter that can electrically set the plurality of filter characteristics.
The calculating section calculates the offset correction data for each of the basic colors so that an offset luminance level of each of the basic colors equals a maximum value of the luminance distribution of offset light of each of the basic colors all over a projection area of the plurality of projectors.
The multiprojection system further includes a section calculating a gamma characteristic distribution of each of the projectors on the basis of a luminance distribution of each image obtained by allowing the image capturing section to capture an image of each basic color at each signal level projected by the projector.
The optical section further has a filter characteristic that does not allow light of wavelength from 650 nm to a predetermined value to pass through.
According to a second aspect of the present invention, there is provided a method of acquiring correction data in a multiprojection system that displays one color image by joining a plurality of color images projected by respective projectors. The method includes: projecting a black level image from the projectors; separating the black level image into images of basic colors constituting the color image using an optical section having a plurality of filter characteristics corresponding to the basic colors; capturing each of the separated images of the basic colors; and calculating offset correction data for each of the basic colors on the basis of a luminance distribution of offset light of each of the basic colors obtained by capturing each of the separated images of the basic colors.
In this method, calculating the offset correction data may include calculating a gamma characteristic distribution of the projector.
Advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.